Recently it has been discovered that large-scale schemes can effectively contribute as much carbon dioxide (CO2) emissions as conventional sources.
Trapped vegetation in the water decays, giving off significant quantities of methane, a greenhouse gas 20 times worse than CO2! Changing in water levels means decaying vegetation is a continuing problem, years after the valley is flooded.
Hydro power from small-scale projects provides cheap, emission-free, reliable electricity. If well designed, they blend in with their surroundings and have minimal negative environmental impact.
An example of a small-scale hydro generator is Barton Lock Hydro Station (left). Situated within a disused pumphouse in Manchester City Centre, it is the first shipping-based canal hydro scheme in the UK.